Introduction to the Circulatory System

Key Questions

• How is glucose transported around the body after digestion?
• How is oxygen transported after inhalation?
• How is carbon dioxide expelled from the body?

The circulatory system plays a crucial role in these processes.

Blood: The Transport Medium

• Misconceptions
  • Human blood is red, not blue, although shade varies with oxygen levels.
  • Veins appear blue/green due to their appearance under the skin, not actual color.
• Functions of Blood
  • Maintains pH, temperature, osmotic pressure (homeostasis).
  • Transports hormones, nutrients, gases.
  • Composed of plasma (liquid) and cellular components.
• Components of Blood
  • Plasma: Contains water, proteins, salts, lipids.
  • Red Blood Cells: Transport gases; contain hemoglobin.
  • White Blood Cells: Fight infections.
  • Platelets: Help blood clot.

Anatomy of the Heart

• Divided into two partitions: oxygenated and deoxygenated.
• Arteries: Carry blood away from the heart (typically oxygen-rich).
• Veins: Carry blood to the heart (typically oxygen-poor).
• Capillaries: Site of oxygen delivery and carbon dioxide pickup.
• Heart Structure
  • 4 chambers: Right atrium, right ventricle, left atrium, left ventricle.
  • Atria have thinner walls than ventricles.
  • Valves prevent backflow of blood.

Pathway of Blood Through the Heart

• Deoxygenated Blood
  1. Travels from the body (e.g., toe) to the right atrium via inferior vena cava.
  2. Passes through tricuspid valve to the right ventricle.
  3. Pulmonary valve to pulmonary artery, then to lungs.
• Oxygenated Blood
  1. Travels back to heart via pulmonary vein to the left atrium.
  2. Mitral valve to left ventricle.
  3. Through aortic valve to the aorta, then throughout the body.

Blood Supply to the Heart

• Coronary Arteries: Branch from the aorta to deliver oxygen and glucose.
• Coronary Veins: Return deoxygenated blood to the right atrium.

Heart Conditions

• Atrial Septal Defect
  • A hole in the septum mixing oxygenated and deoxygenated blood.
  • Can lead to abnormal heartbeat, stroke, or heart failure.
  • Treatment options include medication or surgery.

Summary

• Significant coordination in heart's contractions (cardiac cycle) necessary for proper function.
• Human heart beats over 100,000 times per day.
• Introduction to possible future topics: cardiac cycle, heart conditions.

Further Reading: Explore more on cardiology and advancements in treating cardiovascular conditions.